The subject matter disclosed herein relates to elevator systems. More specifically, the subject disclosure relates to detection of a stuck elevator car or a stuck counterweight.
In order to assure safety, codes require that the car or counterweight must not be lifted, if the counterweight or car becomes stuck in the hoistway, for example on the rails or buffer. Codes prescribe a loss of traction test which must be passed to demonstrate that the car or counterweight will not be lifted if the counterweight or car is stuck. This loss of traction test puts an upper limit on the value of friction or traction between the machine sheave and a suspension member. To meet the loss of traction requirement, one solution includes using friction modifier(s) in the suspension member, which may adversely affect other performance parameters of the suspension member. Another solution includes adding weight to the car to assure that the test can be passed. Both of these solutions add cost and limit performance.